1. Field of the Invention
The invention relates to bleaching systems employing imines and hydrogen peroxide activated with a transition metal catalyst.
2. The Related Art
Sulfonimines in the presence of organic peracids or peracid precursors are excellent bleaches. Their performance is reported in U.S. Pat. No. 5,041,232; U.S. Pat. No. 5,045,223 and U.S. Pat. No. 5,047,163, all to Batal et al. Likewise, imine quaternary salts have been shown to be good oxidants in the presence of organic peracids or peracid precursors. These systems have been described in U.S. Pat. No. 5,360,568; U.S. Pat. No. 5,360,569 and U.S. Pat. No. 5,370,826, all to Madison et al.
Hydrogen peroxide is a good oxidizing agent. It presents economic advantages over organic peracids because it is readily available and inexpensive. The art has however not been able to achieve satisfactory bleaching of stains (e.g. on fabrics or hard surfaces) with hydrogen peroxide as the oxidant.
Accordingly, it is an object of the present invention to provide a bleaching system utilizing hydrogen peroxide as an oxidant in combination with imines to achieve improved efficacy in bleaching stained substrates.
Another object of the present invention is to provide a bleaching system for removing stains from fabrics over a wide temperature range including that of under 60.degree. C., and especially under 30.degree. C.
Still another object of the present invention is to provide a bleaching system capable of removing stains from substrates such as fabrics, household hard surfaces including sinks, toilets and the like, and even dentures.
Yet another object of the present invention is to provide a bleaching system effective in relatively small amounts so as to be commercially cost effective.
Other objects of the present invention will become apparent through the following summary, detailed description and examples.